[mac_truck]

The OPCW also took their own samples, both directly from the victims and from the various contaminated sites.

OPCW did not collect its own samples and it makes no sense that they would do so, weeks after the incident.

[Winniesboy]

They certainly did so. The OPCW took blood samples from the three victims (the third, who tends to be forgotten, being the policeman who found the Skripals on the park bench), and directly from the bench, house, car etc. Indeed they were photographed doing so.